The present invention relates to a seat belt system, more particularly, to a seat belt system for a vehicle which has a double door structure, in which a front door is supported to a vehicular body at its leading edge via a hinge and a rear door is supported to the vehicular body at its trailing edge via a hinge so that both the doors are opened and closed, for example.
A double door structure is well known as disclosed in Japanese Unexamined Patent Publication No. H8-142680. The conventional structure includes a lock pillar extending vertically in the middle portion of a rear opening which is opened and closed by a left-side door and a right-side door in a double door configuration.
Such a double door structure may be provided for an ingress and egress opening on the side of a vehicle. In such a double door structure as described above, a center-pillar extends vertically in the middle portion of the ingress and egress opening, which is beneficial to the rigidity of the vehicle body, but is disadvantageous to the openness of the opening. To enhance the openness, a center-pillar-less structure, i.e. a structure without the center-pillar, is preferable.
As noted, a double door structure combined with the center-pillar-less body is preferred, however, in the case where a seat belt system is so configured that its seat belt webbing is extended from the rear door to the passenger compartment and a seat belt retractor for restricting the passenger is provided in the rear door, an extended length of the seat belt webbing spans between the frontal portion of the rear door and the lower portion of the door opening of the body. This impedes ingress and egress for rear passengers. It should be noted that as used herein, xe2x80x9cpassengerxe2x80x9d refers to occupants of the vehicle generally, including the driver of the vehicle.
In order to solve the problem described above, a rail member may be provided which allows an anchor of the seat belt, especially of a lap belt, to slide in the vehicular longitudinal direction. The rail member is disposed between a floor portion in the vicinity of the outboard side of a front seat and a rear portion thereof. With this configuration, the opening motion of the rear door causes the anchor to slide rearwardly along the rail member, which prevents the seat belt from interfering with the ingress or egress of rear passengers.
In the meantime, it is required to detect weight acting on the front seat for the purpose of deciding whether air bags should be deployed. However, when the rail member is attached to the floor, and when a weight detecting device for detecting weight is provided between the front seat and the floor, the fastening of the seat belt by an occupant in the front seat causes tension in the seat belt to act on the anchor and the lap belt. Thus, the front seat is subjected to tension towards the floor in addition to the weight of the occupant, which may possibly result in the erroneous detection by the weight detecting device.
In view of the above, an object of the present invention is to provide a seat belt system for vehicles, particularly, a seat belt system which does not interfere with the ingress and egress of the rear seat passenger, which can detect the presence of an occupant without being influenced by the seat belt tension to provide the accurate weight detection. In one embodiment, this may be attained by attaching the front end of the rail member which allows the seat belt anchor to slide in the vehicular longitudinal direction substantially on the seat side above a weight detecting device.
According to the present invention, the object is achieved by a seat belt system for a vehicle, comprising a retractor disposed in a rear door for retracting a seat belt webbing for restraining an occupant in a front seat, an anchor of the seat belt webbing disposed laterally adjacent to the front seat, a rail member attached to the vehicle at a front attached portion and a rear attached portion for allowing the anchor of the seat belt webbing to slide in the vehicular longitudinal direction, a weight detecting device disposed between the front seat and a floor panel for detecting weight acting on the front seat, and a buckle capable of engaging a tongue of the seat belt webbing, disposed on the seat above the weight detecting device, wherein the front attached portion of the rail member is attached substantially on the seat above the weight detecting device.
Accordingly, when the seat belt webbing is retractably reeled out from the retractor in the rear door and the tongue of the seat belt webbing engages the buckle, the three-point seat belt restraint configuration for restraining the occupant in the front seat is attained. On the other hand, when the rear door is opened after the seat belt webbing is released, the opening motion of the rear door causes the anchor of the seat belt webbing to move rearwardly along the rail member. This prevents the seat belt webbing from interfering with the ingress and egress of the rear passengers.
Furthermore, when the seat belt webbing is fastened, the presence of passenger can be detected without being influenced by the seat belt tension because the front end of the rail member is attached substantially on the seat above the weight detecting device. This ensures accurate weight detection by the weight detecting device.
Preferably, in one embodiment of the apparatus according to the present invention, the weight detecting device may include a load detecting portion which detects load of the passenger, a base member which supports the load detecting portion, and a load transfer member which transfers load acting on the front seat to the load detecting portion, the front attached portion of the rail member being fixed to the load transfer member. Therefore, there is no need for additional parts to fix the rail member because the rail member is fixed efficiently utilizing the load transfer member of the weight detecting device, thereby reducing the number of parts.
More preferably, the rear portion of the weight detecting device may be located in the vicinity of the rear end portion of a seat cushion of the front seat, the front attached portion of the rail member may be fixed to an extension extending rearwardly from the rear end of the load transfer member, and the rail member may include a curved portion between the front attached portion and a slide portion on which the anchor slides. The curved portion may firstly extend forwardly and downwardly from the front attached portion and then curve upwardly and rearwardly, and further deviate outboardly in the vehicular lateral direction from the front attached portion towards the front end of the slide portion. That is, the anchor point is surely provided avoiding the interference with other parts such as a reclining mechanism provided in the front seat because the rail member is constructed so as to have the curved portion which outboardly deviates towards the front end of the slide portion.
Furthermore, the anchor of the seat belt webbing may preferably have a predetermined longitudinal length along the sliding direction and may be slidably fitted onto the slide portion of the rail member, and the curvature of the curved portion curving upwardly in the rail member may be set with a small curvature as to prevent the anchor from sliding onto the curved portion. Accordingly, the curvature of the curved portion set as above prevents the anchor from sliding onto the curvature which upwardly curves, thereby avoiding the rearward movement of the anchor point through the curved portion after the seat belt webbing is fastened.
Still further, the longitudinal length of the anchor may preferably be set to a predetermined length which prevents the anchor from sliding onto the upwardly curved portion. Accordingly, the anchor is prevented from sliding onto the curved portion by the predetermined longitudinal length of the anchor itself.
Preferably, the vehicle may comprise a door opening, a front door swingably supported at the front edge of the door opening, and the rear door swingably supported at the rear edge of the door opening, wherein the front door and the rear door can cooperatively close the door opening.
These and other objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiment relative to the accompanied drawings.